1. Field of the Invention
This invention relates to electric power-generating devices and more particularly to an apparatus for distributing a source of energy (such as the input torque characteristic of low rotational velocity, high-torque operation of any power source such as wind or water turbine blades) to multiple power generators.
2. Description of the Prior Art
U.S. Pat. No. 6,304,002 granted on Oct. 16, 2001 describes an electric power-generating device comprising a rotor which revolves in response to an external source of mechanical energy. The rotor is coupled to a main power input shaft. The powertrain for wind and ocean current turbines consists of a large, main input power shaft-mounted, rotating bull-gear with stationary smaller pinions mounted around its periphery. The gear teeth on the bull gear rotate past the teeth on pinions, causing the pinions to turn and deliver power to a second stage. The final stage is connected to a plurality of electric generators. This process can be repeated in multiple stages.
As turbines grow in size, the size and weight of individual components grow as well. Wind turbines place these components on top of a tower, presently stretching to over 100 m above the ground, while ocean current turbines are located at sea, where they can only be accessed by boat. The size of the components necessitates very large lifting equipment, making both the land-based cranes and ocean lifting equipment extremely costly.
By dividing the powertrain into smaller components, generating systems receive an element of redundancy. For example, when ten small gearboxes and generators split the system""s load, if one gearbox or generator experiences a fault, the system""s capacity may only be reduced by 10%, allowing the system to remain active. A single generator system loses all of its capacity when the generator experiences a fault.
Briefly, in accordance with the invention, an electric power-generating device comprises a rotor which revolves in response to an external""source of energy, such as wind or water currents or any other power source, to which is coupled a main power input shaft. A torque-dividing gearbox having a circular wheel or gear is coupled to the input shaft driven by the rotor. The torque-dividing gearbox has a plurality of output shafts located around the input shaft. A number of stage-2 wheels or gears are located around a perimeter of the circular gear, half of the stage-2 gears on one side of the circular gear and half on an opposite side of the circular gear. Each one of the stage-2 gears has a stage-2 shaft with a pinion that engages circular gear teeth on the circular gear, and pressure connected to this pinion is a larger circular wheel or gear. Hereafter the assembly of the stage 2 pinion and the pressure connected gear is called the xe2x80x9cintermediate assemblyxe2x80x9d, the pinion in the intermediate assembly is called the xe2x80x9cintermediate pinionxe2x80x9d, and the gear in the intermediate assembly is called the xe2x80x9cintermediate gearxe2x80x9d. Each one of the output shafts engages two intermediate gears, one intermediate gear on one side of the circular gear and one intermediate gear on an opposite side of the circular gear. Each intermediate gear is engages two output shafts, allowing significant size reduction of the intermediate gears and the output shafts. A number of generators are each coupled to respective ones of the output shafts.
In accordance with an aspect of the present invention, the powertrain consists of a large, input power shaft-mounted, rotating bull-gear with stationary smaller intermediate gears mounted around its periphery. Additional stages can be added using the same concept.
The tooth loads on the bull gear are divided n times, where n equals the number of generators, and tooth loads on the intermediate gears and high speed pinions are divided by nxc3x972. The invention has the advantage that the lessened tooth loads allow for smaller gears and bearings, increasing power density and reducing mass and cost.
The invention has the further advantage that the large and expensive bull gear is reduced because it transfers torque from many teeth simultaneously. Furthermore, all the tooth engagements are unidirectional, that is, not reversing, with the advantage of allowing higher loads than other systems such as planetary systems.